1. Field of the Invention
The invention relates generally to visual displays, and more particularly to real-time displays of information in environments that include, but are not limited to military crew stations, nuclear power plants, air traffic control centers, and space stations.
In such environments, large amounts of information must be transmitted from the machine to the human operator, with the result that display space is at a premium. In addition, methods for increasing the rate of information transfer are needed. The latter need is particulaly important in time critical application environments such as crew stations in high speed aircraft.
2. Description of Prior Art
The prior art is replete with display instrumentation that provides real-time information for personnel who are responsible for system operation. The displays are fed by signals derived from microprocessor-controlled circuits which sense system parameters and external factors that affect system functioning.
Even at the present time, many otherwise computerized work stations have electromechanical displays of visual information. However, they are rapidly being replaced by computerized displays. The latter enjoy the important advantage of software (computer-program) control over the information that is presented and over display format, thus obviating the need for hardware changes and for re-wiring of circuits when decisions to revise displays are made.
Some computerized visual displays are essentially CRT (cathode ray tube) versions of the earlier electomechanical dials and meters. However, with the rapid growth of the amount of information that must be communicated to the operator, increasingly sophisticated visual displays are being developed. Examples are instruments for providing an integrated display of aircraft flight system parameters on the screen of a single cathode ray tube (U.S. Pat. No. 4,149,148 to Miller et al, 1979, U.S. Pat. No. 4,247,843 to Miller et al, 1981, and U.S. Pat. No. 4,283,705 to James et al, 1981). Other examples of integrated displays are U.S. Pat. No. 4,543,572 to H. Tanaka et al, 1985, which discloses a road map display of the relationship between vehicle position and destination, and U.S. Pat. No. 4,465,323 to M.J. Kling et al, 1984, which discloses an engine analyzer under the control of a microprocessor which sense engine parameters and displays them on a CRT.
For both electro-mechanical and the CRT displays of the prior art, the human operator acquires information from various stand-alone displays and/or from the the subsections of an integrated CRT display by executing a series of scanning eye movements called saccades. Each saccade with the following fixation period takes about 250 msec., including 20-25 msec. of eye travel time. Suprisingly, only 50-60 msec. of the fixation time is needed to acquire most of the information (Rayner, L., Inhoff, A., Morrison, R., Slowiaczek, M., & Bertera, J. (1981). Masking of foveal and parafoveal vision during eye fixations in reading, Journal of Experimental Psychology: Human Perception and Performance, 7, 167-179). Rayner et al suggest that the remaining time is sued to program the next eye movement, which then occurs with an oculomotor latency of 125-175 msec.
The scientific findings about eye movements cited in the preceding paragraph suggest that a very considerable time saving could be realized if the operator who is monitoring displaying were relieved of the need for moving the eyes from one display element to the next. Basic research in the psychology of reading with a procedure called rapid serial visual presentation (RSVP) lends support to this idea. With RSVP, the linguistically related individual words of a sentence are presented in rapid sequence to the same spatial location. Experimenters who have used this method to study reading report rate as high as 12 words per second, two to three times the rate usually found when skilled readers scan text with saccadic eye movements. For a review with extensive reference to the RSVP literature, see Potter, M. (1984), Rapid serial visual presentation (RSVP): A method for studying language processing. In D. Kieras & M. Just, (Eds.), New Methods in Reading Comprehension Research, New Jersey: Lawrence Erlbaum & Co. Basic research in the psychology of visual search is also relevant. This research shows that search for critical elements (such as a digit among letters) occurs at rates as high as 30 characters per second when eye movements are eliminated by presenting the information sequentially in a single display location. The search rate for similar items presented on an ordinary page is 3-10 characters per second. For a recent review of the search literature, see Chase, W.. (1986), Visual information processing. In K. Boff, L. Kaufman, & J. Thomas, (Eds.), Handbook of Perception and Human Performance, vol II, Human Cognition and Performance, New York: Wiley.